1. Field of the Invention
The present disclosure relates generally to network management.
2. Description of the Related Art
Network services have changed dramatically in recent years, particularly with the migration of sensitive data from the confines of company Intranets to provider networks that carry data for multiple customers over a single network core. For example, voice, video, and other business data, is now commonly sent over virtual private networks (VPNs) established over service provider core networks. Such VPNs provide security and separation by preventing the communication of data between sites that are not part of the same VPN.
As business entities come to rely more and more on service provider core networks, Service Level Agreements play an increasingly important role in their relationship with service providers. SLAs typically contain provisions that specify a guaranteed level of service and penalty provisions for not meeting the specified level of service. In order to measure level of service, tools have been developed that provide information about network traffic that allows network performance to be monitored and also provides insight into the network that aids providers in providing reliable service.
One such tool, commonly referred to as a network probe, actively generates and monitors network traffic to gather information indicative of network performance. Network probes may be implemented on existing network devices, such as routers and switches, or in dedicated devices, such as a dedicated router to offload the required processing. In either case, by actively generating traffic that specifically targets devices in a given network path, network probes may enable the detection of network deficiencies that might not be found using non-intrusive techniques.
Results of probe operations may be kept internally by the device in which the probe is implemented and accessed, for example, via the device command line interface. Results may also be exposed to network management applications, for example, via the simple network management protocol (SNMP). Network probes may be configured to send a notification (commonly referred to as a trap) to a network management system (or fault manager) upon detection of a significant event, such as a loss in connectivity or the reduction in service level below a specified threshold amount. A trap may alert an operator or an administrator the traffic data transport has degraded or failed, indicating a network problem, such as malfunctioning or failing equipment and congestion.
For optimal placement of probes (i.e., what source-destination pairs should be monitored), some knowledge of the VPN topology is required to determine where to optimally place probes. VPN topology is generally defined by the ability to communicate or reach different destinations from different sources (also referred to as “reachability”). Selective placement is important, for example, because it would be a waste of computing resources (e.g., router CPU and memory) to provision a probe to monitor traffic between endpoints that do not actually communicate between each other, such as sites that represent “spokes” that communicate with a common “hub” but not each other.
Particularly in Multiprotocol Label Switching (MPLS) networks, it may be extremely difficult to determine site reachability and, therefore, to discover VPN topology. Conventionally, reachability between MPLS VPN sites is discovered through complex analysis of VPN routing/forwarding instance (VRF). For example, potential reachability may be established between devices which have common imported and exported labeled routes. However, the existence of route-maps and their additional constraints may cause further complexity and uncertainty. As a result, a topology model generated by conventional discovery techniques involving VRF data analysis may be inaccurate.
Accordingly, what is needed is an improved technique for discovering network topology.